This section is intended to introduce the reader to various aspects of art, which may be related to the present embodiments that are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light.
Wireless communication networks are present in many communication systems today. Many of the communication devices used in the systems include one or more antennas for interfacing to the network. These communication devices often include, but are not limited to, set-top boxes, gateways, cellular or wireless telephones, televisions, home computers, media content players, and the like. Further, many of these communication devices may include multiple interfaces for different types of networks. As a result, one or more antennas may be present on or in a communication device.
The antennas used in communication devices may be designed to be mounted directly to a printed circuit board. FIG. 1 illustrates an exemplary antenna designed to be mounted on a printed circuit board located inside a communication device. The exemplary antenna is referred to as an inverted f antenna. FIG. 1 includes a conductive element 110. Element 110 operates with similar characteristics to a monopole antenna over a ground plane. One end of element 120 connects to element 110 at a point that is a predetermined distance from one end of element 110. The other end of element 120 is the interface point to an electrical circuit, such as a communication circuit. The length of element 110 is selected to be approximately one quarter wavelength of the operating frequency of the antenna. The distance from the end of element 110 to the connection point with element 120 is chosen such that the radiation resistance is as close as possible to the operating impedance or resistance for the communication circuit connected to element 120.
The end of element 110 closest to element 120 is connected to one end of another conductive element 130. The other end of element 130 is an interface for connecting to ground. The addition of element 130 is important to the structure of an inverted f antenna. Since the antenna length is usually selected to be less than a full wavelength of the operating frequency for the antenna, the electrical interface for the antenna may electrically operate equivalent to a resistive element in series with a low value capacitive element. Element 130 electrically operates similar to adding an inductor in parallel with the remaining equivalent elements in the antenna. As a result, element 130 reduces the effect of the equivalent series capacitance for the antenna. Finally, the other end of element 110 connects to one end of conductive element 140. Element 140 primarily acts as a support or counter balance to prevent unintentional dislodging from its mounting holes in the printed circuit board during the manufacturing process for the device. The other end of element 140 does not typically connect electrically to a circuit.
Problems often exist with antenna structures that are mounted to a printed circuit board. For instance, the antenna may move or shift from its original mounted position during the manufacturing process. Moving or shifting is particularly problematic with antennas that do not have a balanced center of mass. Although the antenna shown in FIG. 1 adds element 140 to prevent movement or tipping in one direction, the antenna does not sufficiently restrict movement to prevent tilt or shift in other directions. For instance, the antenna may tilt sideways relative to a vertical plane prior to completion of assembly or soldering and remain locked in this tilted position after completion. The shifting or tilt of the antenna structure may cause performance issues due to improper antenna orientation or further due to improper position with respect to other components or circuits. Therefore, there is a need for an improved antenna structure that includes a self supporting feature to address these and other issues.